Draper headers generally include a header frame, an elongate cutter bar along a front edge of the frame including a cutter bar beam which carries a plurality of knife guards for guiding reciprocating movement of a sickle knife across a front edge of the cutter bar. On the header is also mounted a draper assembly including a first and second draper guide roller each arranged at a respective end of the draper assembly spaced apart along the cutter bar with an axis of each roller extending substantially at right angles to the cutter bar, a draper canvas forming a continuous loop of flexible material wrapped around the rollers so as to define a front edge of the canvas adjacent the cutter bar, a rear edge of the canvas spaced rearwardly of the cutter bar, an upper run of the canvas on top of the roller and a lower run of the canvas below the rollers. The cut crop thus falls rearwardly onto the upper run of the canvas and is transported longitudinally of the header. Generally, between the draper rollers there is provided a support plate assembly for the upper run of the draper canvas to prevent sagging.
The header of this type can be used simply for forming a swath in which case the material is carried to a discharge opening of the header and deposited therefrom onto the ground. Headers of this type can also be used for feeding a combine harvester so that the materials are carried to an adapter member positioned at the discharge opening of the header for carrying the materials from the discharge opening into the feeder housing of the combine harvester. Yet further, headers of this type can be used for hay conditioners in which the material from the discharge opening is carried into crushing rolls. It will be appreciated, therefore, that the use of the header is not limited to particular types of agricultural machine but can be used with any such machine in which it is necessary to cut a standing crop and to transport that crop when cut longitudinally of the header for operation thereon.
The draper canvas normally comprises a fabric which is coated with a rubber material which is then vulcanized after forming of the fabric into the required shape and after attachment thereto of transverse slats. There is an interface between the outer surface of the draper canvas and the upper surface of the cutterbar over which the cut crop, and any material carried thereby, will pass as the cut crop is transferred onto the draper canvas. It is generally undesirable for the cut crop and material carried thereby to enter this interface, as it can collect within the internal cavities of the header, particularly in the area between the upper and lower runs of the draper canvas, so as ride on the lower run, tumble and build up heat, and be carried between the canvas and the rollers, to increase friction and wear and decrease canvas and bearing life.
Various seal arrangements have been proposed for the sides or ends of draper and conveyor canvas belts to reduce or prevent infiltration of cut crop and other material, e.g., dust, to reduce the above problems and increase canvas and other component life.
Reference an early seal arrangement disclosed in Paradise U.S. Pat. No. 2,347,365 issued Apr. 25, 1944 which illustrates use of a thicker fabric sealing strip on the end of a draper canvas which is received in and slides along a channel, wherein the top and bottom surfaces of the sealing strip engage and slide along the top and bottom surfaces defining the channel for sealing and preventing infiltration of crop and other material past the channel. However, it can be observed that the bottom surface of the sealing strip also supports the adjacent portion of the draper fabric during the sliding movement, and there is a large gap between the end of the strip and the side of the channel. As a result, the bottom surface of the strip is subject to friction and resulting wear, and will eventually become the sole sealing means to prevent infiltration of cut crop and other material into the inner regions of the draper.
Reference also, Talbot U.S. Pat. No. 5,459,986 issued Oct. 24, 1995 which is reported to have achieved satisfactory seal results and has been used for many years. However, it again provides only a single seal, located between a bottom surface of a rearwardly extending element of the cutter bar and a front edge portion of the upper surface of the canvas. Again, an observed shortcoming, is that as the single seal wears, cut crop will more easily enter the interface between the cutter bar and draper canvas, so as to build up and result in increased friction and canvas wear.
Reference also Shearer U.S. Pat. No. 6,351,931 issued Mar. 5, 2002, which discloses an additional guide bead on the outer surface of the canvas which runs in contact with the edge of the element of the cutter bar, which is reported by the owners of that and the above referenced Talbot patent to have failed to provide expected improvements over the seal arrangement of the Talbot patent. It is also observed that the guide bead presents an upstanding obstacle that can inhibit smooth flow of cut crop, and particularly grain, over the transition from the cutterbar to the draper canvas.
Reference further, Talbot et al. U.S. Pat. No. 7,472,533 issued Jan. 6, 2009, also to the assignee of the above referenced Talbot and Shearer patents, which discloses an arrangement including a resilient strip along the front edge of the draper canvas which cooperates with a rearwardly projecting element of the cutter bar extending over the upper run of the canvas to form a seal. This arrangement eliminates the obstacle of the Shearer patent. However, it is observed that, again, only a single seal interface is provided which can loose effectiveness over time as a result of friction and wear.
What is sought therefore, is a manner of creating a barrier to passage of cut crop and material carried thereby, through the interface between the cutter bar and the draper canvas of a header, which overcomes one or more of the shortcomings set forth above.